Virtual blade inspection

ABSTRACT

A system and method for virtually inspecting a blade stage is disclosed. The system may include a digitizing device for obtaining a three-dimensional model of a shroud of each blade of the blade stage. A computer system may include at least one module configured to perform the following processes: extract a geometric location data of a plurality of reference points of each shroud from a three-dimensional model of a shroud of each blade of the blade stage created by digitizing using a digitizing device; generate a 3D virtual rendering of the shrouds of the blade stage based on the geometric location data and the known dimensions of the blade stage, the three-dimensional virtual rendering including a rendering of the plurality of reference points of each shroud; and inspect the blade stage using the three-dimensional virtual rendering.

BACKGROUND OF THE INVENTION

The disclosure relates generally to machine inspection, and moreparticularly, to a virtual blade inspection including, for example,axial, radial and/or twist deformation.

Blades are used to generate power from a flow of a working fluid indevices such as a turbomachine. In particular, a number of blades may becoupled to a rotor to impart rotational motion to the rotor from a flowof a working fluid thereover. Blades are initially shaped based on idealmodels that create highly efficient blades. Each blade may include ashroud at an outer end thereof that includes a hard face that interactswith a mating hard surface of an adjacent blade's shroud. Hard faces areparts of the shroud that include wear material and come into contactwith one another at a base load to dampen vibration. During turbineengine operation, shrouded turbine blades are subject to high amounts ofdistortion and twist. A contact gap between two adjacent blades iscritical to ensure bucket engagement during operation. As the bladeswear, the contact gap between two adjacent blades increases resulting ininadequate blade engagement. Consequently, blade hard faces oftenrequire restoration during periodic repair processes.

After repair, an inspection is performed in order to ensure the bladeshave been properly restored. As part of the inspection, all of theblades of a particular stage are positioned in place on a rotor wheel byaxially sliding the blades into place on mating couplings on the rotorwheel. The number of blades may vary depending on the blade stage, butis typically a relatively large number, e.g., 92, 100, etc. At thispoint, shims having a known size are placed between each adjacent pairof blade shrouds interacting hard faces. The cumulative dimension of theshims provides a measure of the cumulative dimension of all of thecontact gaps between hard faces of the rotor wheel. A cumulative contactgap that is too large indicates unsuitability of the blades forcontinued use. In addition, an inability to place the shims into placebetween certain adjacent blade shrouds indicates that one or more bladesmay be too twisted for use, i.e., there is no contact gap betweenadjacent shroud hard faces. Further, a maximum allowable gap check mayalso be performed during the inspection. Once the inspection iscomplete, the blades are removed for shipment and installing at a site.This inspection process poses a challenge in that the loading of theblades onto a rotor wheel, shimming all of the contact gaps, measuringthe contact gaps/shims and removing all of blades is very laborintensive and time consuming.

The current process also does not address other structural deformationssuch as axial deformation. Also, radial deformation can lead to theoverlay of shrouds within a wheel, causing binding referred to as‘shingling’.

BRIEF DESCRIPTION OF THE INVENTION

A first aspect of the disclosure provides a computerized method ofvirtually inspecting contact gaps of a blade stage, the blade stagehaving known dimensions, the method comprising: in a computer system:extracting a geometric location data of a hard face plane of each shroudfrom a three-dimensional model of a shroud of each blade of the bladestage created by digitizing using a digitizing device; generating athree-dimensional virtual rendering of the shrouds of the blade stagebased on the geometric location data and the known dimensions of theblade stage, the three-dimensional virtual rendering including arendering of contact gaps between adjacent shrouds; and inspecting theblade stage using the three-dimensional virtual rendering.

A second aspect of the disclosure provides a system for virtuallyinspecting contact gaps of a blade stage, the blade stage having knowndimensions, the system comprising: a computer system including at leastone module configured to perform the following steps: extracting ageometric location data of a hard face plane of each shroud from athree-dimensional model of a shroud of each blade of the blade stagecreated by digitizing using a digitizing device; generating athree-dimensional virtual rendering of the shrouds of the blade stagebased on the geometric location data and the known dimensions of theblade stage, the three-dimensional virtual rendering including arendering of contact gaps between adjacent shrouds; and inspecting theblade stage using the three-dimensional virtual rendering.

A third aspect of the disclosure provides a system for virtuallyinspecting contact gaps of a blade stage, the blade stage having knowndimensions, the system comprising: a digitizing device for obtaining athree-dimensional model of a shroud of each blade of the blade stage; acomputer system including at least one module configured to perform thefollowing steps: extracting a geometric location data of a hard placeplane of each shroud from the three-dimensional model, the extractingincluding identifying an x, y and z coordinate of each hard face planein space, and identifying an angular orientation of each hard face planein space; generating a three-dimensional virtual rendering of theshrouds of the blade stage based on the geometric location data and theknown dimensions of the blade stage, the three-dimensional virtualrendering including a rendering of contact gaps between adjacentshrouds, the generating including calculating a unit normal vector toeach hard face plane, radially positioning each hard face plane relativeto a common axis based on a shroud radius of the blade stage, andcircumferentially positioning each hard face plane about the common axisusing a spacing depending on the number of blades in the blade stage;and inspecting the blade stage using the three-dimensional virtualrendering by at least one of: a) expanding each hard face plane in theunit normal vector direction, and identifying interference betweenadjacent shrouds in response to an expanded hard face planes of adjacentshrouds intersecting; and b) measuring a contact gap between hard faceplanes of each pair of adjacent blades in the three-dimensional virtualrendering, and determining whether at least one contact gap parameterexceeds a respective threshold.

A fourth aspect includes a computerized method of virtually inspectingshrouds of a blade stage, the blade stage having known dimensions, themethod comprising: in a computer system: extracting a geometric locationdata of a plurality of reference points of each shroud from athree-dimensional model of a shroud of each blade of the blade stagecreated by digitizing using a digitizing device; generating athree-dimensional virtual rendering of the shrouds of the blade stagebased on the geometric location data and the known dimensions of theblade stage, the three-dimensional virtual rendering including arendering of the plurality of reference points of each shroud, whereinthe generating includes: radially positioning each shroud relative to acommon axis based on a shroud radius of the blade stage, andcircumferentially positioning each shroud about the common axis using aspacing depending on the number of blades in the blade stage; andinspecting the blade stage using the three-dimensional virtualrendering.

A fifth aspect relates to a system for virtually inspecting a bladestage, the blade stage having known dimensions, the system comprising: acomputer system including at least one module configured to perform thefollowing steps: extracting a geometric location data of a plurality ofreference points of each shroud from a three-dimensional model of ashroud of each blade of the blade stage created by digitizing using adigitizing device; generating a three-dimensional virtual rendering ofthe shrouds of the blade stage based on the geometric location data andthe known dimensions of the blade stage, the three-dimensional virtualrendering including a rendering of the plurality of reference points ofeach shroud, wherein the generating includes: radially positioning eachshroud relative to a common axis based on a shroud radius of the bladestage, and circumferentially positioning each shroud about the commonaxis using a spacing depending on the number of blades in the bladestage; and inspecting the blade stage using the three-dimensionalvirtual rendering.

A sixth aspect includes a system for virtually inspecting a blade stage,the blade stage having known dimensions, the system comprising: adigitizing device for obtaining a three-dimensional model of at least ashroud of each blade of the blade stage; a computer system including atleast one module configured to perform the following steps: extracting ageometric location data of a plurality of reference points of eachshroud from a three-dimensional model of a shroud of each blade of theblade stage created by digitizing using a digitizing device; generatinga three-dimensional virtual rendering of the shrouds of the blade stagebased on the geometric location data and the known dimensions of theblade stage, the three-dimensional virtual rendering including arendering of the plurality of reference points of each shroud, whereinthe generating includes: radially positioning each shroud relative to acommon axis based on a shroud radius of the blade stage, andcircumferentially positioning each shroud about the common axis using aspacing depending on the number of blades in the blade stage, inspectingthe blade stage using the three-dimensional virtual rendering byidentifying at least one of an axial deformation, a radial deformation,a twist deformation, and a contact gap violation; and modifying at leastone blade to at least reduce the at least one of the axial deformation,the radial deformation, the twist deformation, and the contact gapviolation.

The illustrative aspects of the present disclosure are designed to solvethe problems herein described and/or other problems not discussed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this disclosure will be more readilyunderstood from the following detailed description of the variousaspects of the disclosure taken in conjunction with the accompanyingdrawings that depict various embodiments of the disclosure, in which:

FIG. 1 shows a block diagram of an illustrative environment of aninspection system for virtually inspecting a blade stage according toembodiments of the disclosure.

FIG. 2 shows a top view of a three-dimensional model of a shroud of ablade according to embodiments of the disclosure.

FIG. 3 shows an enlarged end view of a three dimensional virtualrendering of a hard face plane of a shroud according to embodiments ofthe disclosure.

FIG. 4 shows a top view of a three dimensional virtual rendering of apair of adjacent shrouds according to embodiments of the disclosure.

FIG. 5 shows a top perspective view of a three dimensional virtualrendering of a pair of adjacent shrouds according to embodiments of thedisclosure.

FIG. 6 shows a bottom perspective view of a three dimensional virtualrendering of a pair of adjacent shrouds according to embodiments of thedisclosure.

FIG. 7 shows a top view of a three-dimensional model of a shroud of ablade according to embodiments of the disclosure.

FIG. 8 shows a three dimensional virtual rendering of a blade stageaccording to embodiments of the disclosure.

FIG. 9 shows an enlarged plan view of a number of shroud ends accordingto embodiments of the disclosure.

FIGS. 10-13 show enlarged views of two examples of shroud endsundergoing inspection according to embodiments of the disclosure.

It is noted that the drawings of the disclosure are not to scale. Thedrawings are intended to depict only typical aspects of the disclosure,and therefore should not be considered as limiting the scope of thedisclosure. In the drawings, like numbering represents like elementsbetween the drawings.

DETAILED DESCRIPTION OF THE INVENTION

As indicated above, the disclosure provides for virtual bladeinspection. Embodiments of the disclosure may include a computerizedmethod and a system for virtually inspecting contact gaps of a bladestage of, for example, a turbomachine. The blade stage being inspectedhas known dimensions, i.e., outer radius, circumference, inner radius,number of blades, etc. In other embodiments, the inspection system mayemploy a number of vertical reference points on a hard face plane toinspect contact gaps. In further embodiments, the inspection system mayinspect contact gaps, and/or a variety of deformations such as an axial,radial and/or twist deformation.

Referring now to FIG. 1, a block diagram of an illustrative environment100 for virtually inspecting a blade stage according to embodiments ofthe disclosure is shown. To this extent, environment 100 includes acomputer infrastructure 102 that can perform the various process stepsdescribed herein for virtually inspecting a blade stage. In particular,computer infrastructure 102 is shown including a computing device orsystem 104 that comprises an inspection system 106, which enablescomputing device 104 to virtually inspect a blade stage by performingthe process steps of the disclosure.

Computing device 104 is shown including a memory 112, a processor (PU)114, an input/output (I/O) interface 116, and a bus 118. Further,computing device 104 is shown in communication with an external I/Odevice/resource 120 and a storage system 122. As is known in the art, ingeneral, processor 114 executes computer program code, such asinspection system 106, that is stored in memory 112 and/or storagesystem 122. While executing computer program code, processor 114 canread and/or write data, such as digitized three-dimensional models of ashroud of a blade, to/from memory 112, storage system 122, and/or I/Ointerface 116. Bus 118 provides a communications link between each ofthe components in computing device 104. I/O device 118 can comprise anydevice that enables a user to interact with computing device 104 or anydevice that enables computing device 104 to communicate with one or moreother computing devices. Input/output devices (including but not limitedto keyboards, displays, pointing devices, etc.) can be coupled to thesystem either directly or through intervening I/O controllers.

In any event, computing device 104 can comprise any general purposecomputing article of manufacture capable of executing computer programcode installed by a user (e.g., a personal computer, server, handhelddevice, etc.). However, it is understood that computing device 104 andinspection system 106 are only representative of various possibleequivalent computing devices that may perform the various process stepsof the disclosure. To this extent, in other embodiments, computingdevice 104 can comprise any specific purpose computing article ofmanufacture comprising hardware and/or computer program code forperforming specific functions, any computing article of manufacture thatcomprises a combination of specific purpose and general purposehardware/software, or the like. In each case, the program code andhardware can be created using standard programming and engineeringtechniques, respectively.

Similarly, computer infrastructure 102 is only illustrative of varioustypes of computer infrastructures for implementing the disclosure. Forexample, in one embodiment, computer infrastructure 102 comprises two ormore computing devices (e.g., a server cluster) that communicate overany type of wired and/or wireless communications link, such as anetwork, a shared memory, or the like, to perform the various processsteps of the disclosure. When the communications link comprises anetwork, the network can comprise any combination of one or more typesof networks (e.g., the Internet, a wide area network, a local areanetwork, a virtual private network, etc.). Network adapters may also becoupled to the system to enable the data processing system to becomecoupled to other data processing systems or remote printers or storagedevices through intervening private or public networks. Modems, cablemodem and Ethernet cards are just a few of the currently available typesof network adapters. Regardless, communications between the computingdevices may utilize any combination of various types of transmissiontechniques.

As previously mentioned and discussed further below, inspection system106 enables computing infrastructure 102 to virtually inspect a bladestage of, for example, a turbomachine. To this extent, inspection system106 is shown including a number of modules 124. Operation of each ofthese modules is generally discussed herein. However, it is understoodthat some of the various systems shown in FIG. 1 can be implementedindependently, combined, and/or stored in memory for one or moreseparate computing devices that are included in computer infrastructure102. Further, it is understood that some of the systems and/orfunctionality may not be implemented, or additional systems and/orfunctionality may be included as part of environment 100.

Environment 100 may also include a digitizing device 130 for creating athree-dimensional (3D) model 132 (shown in storage system 122) of ashroud 134 of each blade of the blade stage by digitizing. As usedherein, “digitizing” includes any now known or later developed method ofcreating three-dimensional coordinates of at least a portion of a part.Digitizing device 130 may include a mechanical apparatus such as thosethat employ a tracing tip, gauges or indicators, or articulated arms ormay include an optical system such as those that employ photogrammetrytechniques or a laser scanner or tracker or displacement sensors orother structured light or camera. In any event, the digitizing creates alarge number of coordinates in a three-dimensional space such that 3Dmodel 132 takes the form of a mesh on a display. Each shroud 134 may bedigitized in a disassembled state apart from a respective rotor wheel,and independent of other shrouds. Any appropriate fixture may beemployed for supporting and holding each shroud in a uniform mannerduring the digitizing. While FIG. 1 is illustrated including adigitizing device 130 for digitizing shrouds 134, it is understood thatembodiments of the disclosure call for “obtaining” a three-dimensionalmodel of a shroud of each blade of the blade stage by digitizing using adigitizing device. Consequently, it is understood that embodiments ofthe method may employ a 3D model 132 that is not directly generated butobtained from a third party that performs the digitization. When thedata is not generated by digitizing device 130 directly, it isunderstood that another system/component can be implemented apart fromthe system/component shown, which generates 3D model 132 and provides itto inspection system 106/or stores the data for access by the system. Inthis regard, various systems and components as described may “obtain”data such as 3D model 132 of a shroud, etc. It is understood that thecorresponding data can be obtained using any solution. For example, thecorresponding system/component can retrieve the data from one or moredata stores (e.g., a database), or receive the data from anothersystem/component, and/or the like.

Referring to FIG. 2, an illustrative 3D model 132 of shroud 134 of ablade 140 is illustrated. 3D model 132 illustrates a first hard faceplane D1 of a hard face 142 at a first circumferential end 144 of shroud134, and a second hard face plane D2 of a second hard face 146 at anopposing, second circumferential end 148. As understood in the art,blade 140 is slid into a rotor wheel in an axial direction x thatparallels a rotor axis (not shown), and adjacent blades 140 mate alonghard faces 142 and 146. 3D model 132, as noted, may be obtained usingdigitizing device 130 (FIG. 1) that may include a mechanical apparatussuch as those that employ a tracing tip, or may include an opticalsystem such as those that employ a laser scanner or other structuredlight. FIG. 3 shows a rendering from a digitizing device in the form ofa structured light device created by a 3D light scanner such as but notlimited to: an ATOS industrial 3D scanner available from GOM GmbH, or aSteinbichler COMET L3D scanner available from Carl Zeiss OptotechnikGmbH.

Continuing with FIGS. 2-7, inspection system 106 (FIG. 1) extractsgeometric location data of a plurality of reference points of eachshroud in 3D model 132 of a shroud 134 of each blade 140 of the bladestage. In FIGS. 2-7, the x axis extends parallel to a rotor axis (notshown), the y axis extends in a first radial direction laterally fromthe rotor axis, and the z axis extends in a second radial directionvertically from the rotor axis (see legends).

In one embodiment, as shown in FIG. 2, the geometric location data mayinclude reference points of hard face plane(s) D1, D2 of each shroud 134from 3D model 132. The extracting of the geometric location data mayinclude, for example, identifying an x, y and z coordinate of each hardface plane D1, D2 in space. Consequently, in FIG. 2, each hard faceplane D1, D2 includes a number of data points in three-dimensional spacesuch that a best fit plane can be ascertained. In another embodiment,shown in the enlarged end view of FIG. 3 of hard faces 142, 146,inspection system 106 may extract the geometric location data byidentifying an x, y and z coordinate of a plurality of verticalreference points, e.g., 147A-C, along a hard face 142, 146 (hard faceplanes D1, D2) of each shroud 134 in space. As each blade 134 is fixedin a holder or support in an identical fashion to every other bladeduring digitizing, the x, y, z coordinates share a common origin as areference. The extracting may also include identifying a compoundangular orientation a (FIG. 2) of each hard face plane D1, D2 in space(only one shown). The extraction thus provides geometric location dataof each hard face plane D1, D2 relative to a common reference point.

Referring to FIGS. 4-7, in other embodiments in which, for example,deformations are identified, only specific reference points may beextracted. For example, as shown in FIG. 4, for use in identifying anaxial deformation as will be described herein, inspection system 106 mayextract the geometric location data by identifying x coordinates of apair of corresponding axial reference points 170, 172 of hard faceplanes D1, D2 (of hard faces 142, 146, respectively) for each pair ofadjacent shrouds 134A, 134B in space, respectively. The x coordinatesmay be the same as or different than those extracted relative to FIG. 2.In another example, shown FIGS. 5 and 6, for use in identifying a radialdeformation as will be described herein, inspection system 106 mayextract the geometric location data by identifying, for each shroud134A, 134B in space, a z coordinate of a selected radial point. As shownin FIG. 5, the selected radial point (z coordinate) may be an outermostradial point 174, 176 of a hard face plane D1, D2, respectively, or asshown in FIG. 6, the selected radial point (z coordinate) may be aninnermost radial point 178, 180 of hard face plane D1, D2, respectively.In FIG. 5, outermost radial point is on an outermost surface of ahalf-rib 183 extending from an outer facing surface 186 of shroud 134A,134B. The z coordinates may be the same as or different than thoseextracted relative to FIG. 2. In yet another example, as shown in FIG.7, inspection system 106 may extract the geometric location data byidentifying a pair of x coordinate reference points 182, 184 for eachshroud 134 in space. In this example, the x-coordinate reference points182, 184 are on half rib 183 extending from an outer facing surface 186of shroud 134. The use of each embodiment of extraction of referencepoint(s) will be described in greater detail herein.

As shown in FIG. 8, inspection system 106 (FIG. 1) generates athree-dimensional (3D) virtual rendering 150 of shrouds 152 (two denotedwith boxes) of blade stage 154 based on the geometric location data(FIG. 2) of each blade, and the known dimensions of the blade stage 154.The generating of 3D virtual rendering 150 may include radiallypositioning each shroud 152 relative to a common axis (e.g., y axis)based on a shroud radius R of blade stage 154. In one embodiment, therendering may include radially positioning at least each hard face planeD1, D2 (one pair collectively referenced as 156 in FIG. 8, but producedfor each blade) relative to a common axis (e.g., y axis) based on ashroud radius R of blade stage 154. Shroud radius R is a known dimensionof a blade stage 154 upon which a particular z axis offset for shrouds152 (blades of blade stage 154) can be positioned in the 3D virtualrendering 150, e.g., in FIG. 8 from X, Y, Z coordinate at center toworking x, y, z coordinates. In addition, the generating may includecircumferentially positioning each hard face plane D1, D2 (FIG. 4) aboutcommon axis (e.g., y axis) using a spacing depending on the number ofblades in blade stage 150. The circumferential positioning may includeassigning each blade 152 a clocking angle β equal to 360° divided by thenumber of blades in blade stage 154. In the example shown, 92 blades areprovided, so the clocking angle β or circumferential spacing is 3.91°;other angles would be used for different number of blades. As usedherein, “rendering” has been shown as creating a virtual image for thepurposes of description. It is emphasized, however, that rendering doesnot necessarily require creating an image, and can include anyelectronic representation.

FIG. 9 shows a radially inward and enlarged view of examples of expandedhard face planes D1, D2, as will be described herein. Expanded hard faceplanes are also illustrated collectively for each shroud 152 asreference 156 in FIG. 8.

FIGS. 10 and 11 show two examples of enlarged schematic view of hardface planes D1, D2—as are illustrated collectively for each shroud 152as reference 156 in FIGS. 8 and 9. In the examples, hard face plane D1is a leading edge plane and hard face plane D2 is a trailing edge plane.FIG. 10 illustrates a situation where a contact gap CG exists, and FIG.11 illustrates an interference situation where no gap exists, which isone example of a contact gap violation as defined elsewhere herein.Thus, 3D virtual rendering 150 (FIG. 3) includes a rendering of contactgaps CG, where present, between adjacent shrouds for all of shrouds 152(FIG. 3) in blade stage 154 (FIG. 3). Consequently, 3D virtual rendering150 provides a virtual model of blade stage 154 without having toactually put each blade into position on a rotor wheel, thus reducingthe time and labor necessary to evaluate shroud repair work. As alsoshown in FIGS. 10 and 11, the generating may also include calculating aunit normal vector (UNV) to each hard face plane D1, D2, which indicatesa direction perpendicular to each plane. The function of the unit normalvectors will be described herein.

Inspection system 106 may also perform a variety of inspection steps ofblade stage 154 (FIG. 8), including particular (virtual) shrouds 154thereof, using 3D virtual rendering 150 (FIG. 8). In particular,inspection system 106 can identify, as will be described, at least oneof an axial deformation, a radial deformation, a twist deformation, anda contact gap violation.

In one embodiment, with regard to identifying a contact gap violation,as shown in FIGS. 12 and 13, the inspecting may include: expanding eachhard face plane D1, D2 in the unit normal vector (UNV) direction. A“contact gap violation” may include any situation where the minimum ormaximum contact gap is not as specified, e.g., where an interferenceexists or too large of a gap exists. As shown in FIGS. 12 and 13, theexpansion results in a rectangular shape 160, 162 projectingperpendicularly from each respective plane D1, D2, respectively. Basedon the expansion, inspection system 106 can identify interference, asshown in FIG. 13, between adjacent shrouds in response to the expandedhard face planes 160, 162 of adjacent shrouds intersecting, i.e., acontact gap violation. In contrast, in FIG. 12, no interference isidentified because expanded hard face planes 160, 162 of hard faceplanes D1, D2, respectively, do not intersect. The inspection may occurfor each pair of adjacent shrouds 152 (FIG. 8) in 3D virtual rendering150 (FIG. 8), thus eliminating the need to physically check each contactgap. Where a plurality of vertical reference points 147A-C (FIG. 4) areextracted, the above-described process can be repeated at each verticalpoint, thus checking for various contact gap violations (i.e.,intersection) along a vertical extent of hard face planes D1, D2.

In another embodiment, inspection system 106 may measure a contact gapCG (FIG. 10) between hard face planes D1, D2 of each pair of adjacentblades 152 (FIG. 8) in 3D virtual rendering 150 (FIG. 8). Themeasurements may be used in a number of ways. In one embodiment,inspection system 106 may use the measured contact gaps to identify aminimum contact gap amongst the contact gaps, and then determine whetherthe minimum contact gap exceeds a threshold. For example, if noindividual contact gap can be less than a certain dimension, thisprocess would identify which pair(s) of shrouds 152 were out ofcompliance. Similarly, inspection system 106 may use the measuredcontact gaps to identify a maximum contact gap amongst the contact gaps,and then determine whether the maximum contact gap exceeds a threshold.For example, if no individual contact gap can be greater than a certaindimension, this process would identify which pair(s) of shrouds 152 wereout of compliance.

In another embodiment, where plurality of vertical reference points,147A-C (FIG. 4), on each hard face plane D1, D2 are identified,inspection system 106 may measure a contact gap between hard face planesD1, D2 of each pair of adjacent blades in the three-dimensional virtualrendering at each of plurality of vertical reference points, 147A-C(FIG. 4). That is, for each pair of adjacent shrouds 134A, 134B, aplurality of contact gaps are measured. In this case, a minimum (ormaximum) contact gap amongst the contact gaps at each of the pluralityof vertical reference points may be identified, and a contact gapviolation may be identified, as noted herein, by determining whether theminimum (or maximum) contact gap exceeds a threshold. As noted, acontact gap violation may include any situation where the minimum ormaximum contact gap is not as specified. Further, in another embodiment,regardless of whether a single or many contact gaps are measured,inspection system 106 may calculate a cumulative contact gap by summingthe contact gaps. That is, for all of the shroud pairs, the sum of thecontact gaps may be summed. Where more than one contact gap for eachpair is identified, the summing may be across those contact gaps at thesame vertical position (e.g., for all gaps at point 147A), or may becumulative across all contact gaps (e.g., for all gaps at points147A-C). In any event, the cumulative contact gap may be used determinewhether the cumulative contact gap exceeds a threshold, which mayindicate a repair or modification is necessary.

Angular orientation of hard face planes D1, D2 and other features ofshrouds 134 can also be evaluated using 3D virtual rendering 150 (FIG.8). In one embodiment, with reference to FIG. 7, based on identifiedx-coordinates 182, 184, inspection system 106 may measure a twist amountγ of each shroud 134 in space by measuring a shift in space of each ofthe pair of x coordinates 182, 184 thereof relative to an expectedlocation of each x coordinate (using basic geometric calculations). Thatis, by measuring a distance each x coordinate reference point 182, 184has moved from an expected location (stored in memory of system 100), atwist amount γ of shroud 134 can be identified. Based on one or moretwist amounts γ individually exceeding a threshold, e.g., 1°, inspectionsystem 106 can determine a twist deformation exists, necessitatingreplacement or repair of one or more shrouds 134 including the twists.Although shroud 134 in FIG. 7 has been shown to have twisted in aparticular direction, e.g., counterclockwise, the twist can occur in theother direction, i.e., clockwise.

In another embodiment, axial and/or radial deformations can beidentified using 3D virtual rendering 150 (FIG. 8).

Referring to FIG. 4, an axial deformation may include a lack of overlapor too little overlap of hard face planes D1, D2 of pairs of adjacentshrouds 134A, 134B in a generally axial (x) direction. The axialdirection, as illustrated, may not be perfectly aligned with the x axis.In order to identify an axial deformation, inspection system 106 maymeasure an axial overlap (AO) between hard face planes D1, D2 of eachpair of adjacent blades 134A, 134B in 3D virtual rendering 132 based onthe x coordinates of the pair of corresponding axial reference points170, 172. That is, knowing the extracted position of x coordinates atpoint 170 on hard face 142 and point 172 on hard face 144, an axialoverlap (AO) can be measured using, e.g., simple geometric calculations.Once an axial overlap (AO) is known, inspection system 106 may identifyan axial deformation by determining whether one or more axial overlapsindividually exceed a threshold, e.g., 2 cm. In another embodiment,inspection system 106 measuring axial overlap (AO) may includecalculating an axial areal overlap, i.e., a percentage of an area ofeach hard face plane D1, D2 that overlaps. That is, knowing points 170,172 and an area of each hard face plane D1, D2 (e.g., shaded area inFIG. 3), inspection system 106 may calculate the amount of axial arealoverlap. The areal extent of each hard face plane D1, D2 (shaded area inFIG. 3) can be determined in any consistent fashion desired by a user,e.g., that of the inverted T-shape of the plane or some sub-regionthereof. Inspection system 106 can then determine an axial deformationexists by determining whether one or more axial areal overlaps exceed athreshold, e.g., 50%.

Referring to FIGS. 5 and 6, a radial deformation may include a lack ofoverlap or too little overlap of hard face planes D1, D2 of pairs ofadjacent shrouds 134A, 134B in a radial (z) direction. In order toidentify a radial deformation, inspection system 106 may measure aradial shift (Rs) between each pair of adjacent blades 134A, 134B in 3Dvirtual rendering 132 based on the x coordinates of the pair ofcorresponding axial reference points, i.e., either outermost radialpoints 174, 176 (FIG. 5) or innermost radial points 178, 180 (FIG. 6).That is, knowing the extracted position of z coordinates, e.g., at point174 on shroud 134A and point 176 on shroud 134B, a radial shift (Rs) canbe measured using simple geometric calculations. Once a radial shift(Rs) is known, inspection system 106 may identify a radial deformationby determining whether one or more radial shifts (Rs) (see FIG. 5)individually exceed a threshold, e.g., 1 cm. In another embodiment,inspection system 106 measuring radial shift (Rs) may includecalculating a radial areal overlap, i.e., a percentage of each hard faceplane D1, D2 area that radial overlaps. That is, knowing points 174, 176(or 178, 180) and an area of each hard face plane D1, D2 (e.g., shadedarea FIG. 3), inspection system 106 may calculate the amount of radialareal overlap. The areal extent of each hard face plane D1, D2 (FIG. 4)can be determined in any consistent fashion desired by a user.Inspection system 106 can then determine a radial deformation exists bydetermining whether one or more axial areal overlaps exceed a threshold,e.g., 50%.

Regardless of the form of shroud flaw identified, based on theinspecting performed by inspection system 106, an operator may modify atleast one blade 140 to at least reduce the at least one of the axialdeformation, the radial deformation, the twist deformation, and thecontact gap violation. Any modifying of one or more blades that may benecessary can be carried out based on results from inspection system106. The modifications may include any now known or later developedchanges such as replacement, removal or addition of material of hardfaces 142, 146 or other parts of shrouds 134 to modify, e.g., contactgap distances and/or angles, radial or axial positioning, twisting, etc.In addition, particular shrouds 134 may have their position changedwithin a particular blade stage. For example, referring to FIG. 8, acircumferential position of at least one blade within a blade stagebased on the 3D virtual rendering can be changed. As understood in theart, blade stages typically undergo a moment weight balancing to ensurethe blade stage is balanced weight-wise to prevent, for example,undesired vibration. Once a circumferential position of a blade has beenchanged (virtually) by inspection system 106, the system can ensuremoment weight balancing of the revised blade stage does not exceed a(imbalance) threshold, which may vary depending on many factors such asthe size of the turbine. In one non-limiting example, a particularweight balancing may range from 60 to 66 gram-millimeters. This processcan be carried out by inspection system 106 verifying in a conventionalmanner that the blade stage does not exceed the imbalance threshold. Inany event, inspection system 106 can be employed repeatedly oncemodifications have been made to ensure blades 140 are properly repairedand positioned before being re-used, and to achieve optimal results forany of the flaws described herein.

The herein described inspection system 106 and related methodology andsoftware allows for characterization of various physical characteristicsto improve blade engagement and reduce potential life reductions, andassists in ensuring blades assemble properly. It also eliminates theneed for hard fixturing and related physical measurement techniques thatare time consuming and labor intensive.

As will be appreciated by one skilled in the art, embodiments of thepresent disclosure may be embodied as a system, method or computerprogram product. Accordingly, the present disclosure may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, the present disclosure may take the form of a computerprogram product embodied in any tangible medium of expression havingcomputer-usable program code embodied in the medium.

Any combination of one or more non-transitory computer usable orcomputer readable medium(s) may be utilized. The computer-usable orcomputer-readable medium may be, for example but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, device, or propagation medium. Morespecific examples (a non-exhaustive list) of the computer-readablemedium would include the following: an electrical connection having oneor more wires, a portable computer diskette, a hard disk, a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM or Flash memory), an optical fiber, a portablecompact disc read-only memory (CD-ROM), an optical storage device, atransmission media such as those supporting the Internet or an intranet,or a magnetic storage device. Note that the computer-usable orcomputer-readable medium could even be paper or another suitable mediumupon which the program is printed, as the program can be electronicallycaptured, via, for instance, optical scanning of the paper or othermedium, then compiled, interpreted, or otherwise processed in a suitablemanner, if necessary, and then stored in a computer memory. In thecontext of this document, a computer-usable or computer-readable mediummay be any medium that can contain, store, communicate, propagate, ortransport the program for use by or in connection with the instructionexecution system, apparatus, or device. The computer-usable medium mayinclude a propagated data signal with the computer-usable program codeembodied therewith, either in baseband or as part of a carrier wave. Thecomputer usable program code may be transmitted using any appropriatemedium, including but not limited to wireless, wireline, optical fibercable, RF, etc.

Computer program code for carrying out operations of the presentdisclosure may be written in any combination of one or more programminglanguages, including an object oriented programming language such asJava, Smalltalk, C++ or the like and conventional procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The program code may execute entirely on the user's computer,partly on the user's computer, as a stand-alone software package, partlyon the user's computer and partly on a remote computer or entirely onthe remote computer or server. In the latter scenario, the remotecomputer may be connected to the user's computer through any type ofnetwork, including a local area network (LAN) or a wide area network(WAN), or the connection may be made to an external computer (forexample, through the Internet using an Internet Service Provider).

The present disclosure is described herein with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of the disclosure. Itwill be understood that each block of the flowchart illustrations and/orblock diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block or blocks.

These computer program instructions may also be stored in acomputer-readable medium that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablemedium produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions which execute on the computer or other programmableapparatus provide processes for implementing the functions/actsspecified in the flowchart and/or block diagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present disclosure. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The foregoing drawings show some of the processing associated accordingto several embodiments of this disclosure. In this regard, each drawingwithin a flow of the drawings represents a process associated withembodiments of the method described. It should also be noted that insome alternative implementations, the acts noted in the drawings orblocks may occur out of the order noted in the figure or, for example,may in fact be executed substantially concurrently or in the reverseorder, depending upon the act involved. Also, one of ordinary skill inthe art will recognize that additional blocks that describe theprocessing may be added.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

1. A computerized method of virtually inspecting shrouds of a bladestage, the blade stage having known dimensions, the method comprising:in a computer system: extracting a geometric location data of aplurality of reference points of each shroud from a three-dimensionalmodel of a shroud of each blade of the blade stage created by digitizingusing a digitizing device; generating a three-dimensional virtualrendering of the shrouds of the blade stage based on the geometriclocation data and the known dimensions of the blade stage, thethree-dimensional virtual rendering including a rendering of theplurality of reference points of each shroud, wherein the generatingincludes: radially positioning each shroud relative to a common axisbased on a shroud radius of the blade stage, and circumferentiallypositioning each shroud about the common axis using a spacing dependingon the number of blades in the blade stage; and inspecting the bladestage using the three-dimensional virtual rendering.
 2. The method ofclaim 1, wherein the inspecting includes: identifying at least one of anaxial deformation, a radial deformation, a twist deformation, and acontact gap violation, and further comprising modifying at least oneblade to at least reduce the at least one of the axial deformation, theradial deformation, the twist deformation, and the contact gapviolation.
 3. The method of claim 1, wherein the extracting thegeometric location data includes: identifying x coordinates of a pair ofcorresponding axial reference points of a hard face plane for each pairof adjacent shrouds in space; and wherein the inspecting includes:measuring an axial overlap between hard face planes of each pair ofadjacent blades in the three-dimensional virtual rendering based on thex coordinates of the pair of corresponding axial reference points, andidentifying an axial deformation by determining whether an axial overlapindividually exceeds a threshold.
 4. The method of claim 3, wherein themeasuring the axial overlap includes calculating an axial areal overlap,and the determining includes determining whether an axial areal overlapexceeds a threshold.
 5. The method of claim 1, wherein the extractingthe geometric location data includes: identifying, for each shroud inspace, a z coordinate of a selected radial point chosen from the groupconsisting of an outermost radial point of a hard face plane and aninnermost radial point of the hard face plane; and wherein theinspecting includes: measuring a radial shift between the selectedradial point of each pair of adjacent blades in the three-dimensionalvirtual rendering, and identifying a radial deformation by determiningwhether one or more radial shifts individually exceed a threshold. 6.The method of claim 5, wherein the measuring the radial shift includescalculating a radial areal overlap, and the determining includesdetermining whether a radial areal overlap individually exceeds athreshold.
 7. The method of claim 1, wherein the extracting thegeometric location data includes: identifying a pair of x coordinatesfor each shroud in space; and wherein the inspecting includes: measuringa twist amount of each shroud in space by measuring a shift in space ofeach of the pair of x coordinates thereof relative to an expectedlocation of each x coordinate, and identifying a twist deformation bydetermining whether one or more twist amounts individually exceed athreshold.
 8. The method of claim 1, wherein the extracting thegeometric location data includes: identifying an x, y and z coordinateof a plurality of vertical reference points along a hard face plane ofeach shroud in space, and identifying an angular orientation of eachhard face plane in space; and wherein the inspecting includes: measuringa contact gap between hard face planes of each pair of adjacent bladesin the three-dimensional virtual rendering at each of the plurality ofvertical reference points on each hard face plane, identifying a minimumcontact gap amongst the contact gaps at each of the plurality ofvertical reference points, and identifying a contact gap violation bydetermining whether the minimum contact gap exceeds a threshold.
 9. Themethod of claim 1, further comprising: based on the inspecting, changinga circumferential position of at least one blade within the blade stagewithin the three-dimensional virtual rendering of the shrouds of theblade stage; and ensuring a moment weight balancing of the blade stagedoes not exceed a threshold.
 10. A system for virtually inspecting ablade stage, the blade stage having known dimensions, the systemcomprising: a computer system including a processor connected to amemory and at least one module, the module configured to perform thefollowing processes: extracting a geometric location data of a pluralityof reference points of each shroud from a three-dimensional model of ashroud of each blade of the blade stage created by digitizing using adigitizing device; generating a three-dimensional virtual rendering ofthe shrouds of the blade stage based on the geometric location data andthe known dimensions of the blade stage, the three-dimensional virtualrendering including a rendering of the plurality of reference points ofeach shroud, wherein the generating includes: radially positioning eachshroud relative to a common axis based on a shroud radius of the bladestage, and circumferentially positioning each shroud about the commonaxis using a spacing depending on the number of blades in the bladestage; and inspecting the blade stage using the three-dimensionalvirtual rendering.
 11. The system of claim 10, wherein the inspectingincludes: identifying at least one of an axial deformation, a radialdeformation, a twist deformation, and a contact gap violation, andfurther comprising modifying at least one blade to at least reduce theat least one of the axial deformation, the radial deformation, the twistdeformation, and the contact gap violation.
 12. The system of claim 10,wherein the extracting the geometric location data includes: identifyingx coordinates of a pair of corresponding axial reference points of thehard face planes for each pair of adjacent shrouds in space; and whereinthe inspecting includes: measuring an axial overlap between hard faceplanes of each pair of adjacent blades in the three-dimensional virtualrendering based on the x coordinates of the pair of corresponding axialreference points, and identifying an axial deformation by determiningwhether an axial overlap individually exceeds a threshold.
 13. Thesystem of claim 12, wherein the measuring the axial overlap includescalculating an axial areal overlap, and the determining includesdetermining whether one or more axial areal overlaps exceed a threshold.14. The system of claim 10, wherein the extracting the geometriclocation data includes: identifying, for each shroud in space, a zcoordinate of a selected radial point chosen from the group consistingof an outermost radial point of a hard face plane and an innermostradial point of the hard face plane; and wherein the inspectingincludes: measuring a radial shift between the selected radial point ofeach pair of adjacent blades in the three-dimensional virtual rendering,and identifying a radial deformation by determining whether one or moreradial shifts individually exceed a threshold.
 15. The system of claim14, wherein the measuring the radial shift includes calculating a radialareal overlap, and the determining includes determining whether a radialareal overlap individually exceeds a threshold.
 16. The system of claim10, wherein the extracting the geometric location data includes:identifying a pair of x coordinates for each shroud in space; andwherein the inspecting includes: measuring a twist amount of each shroudin space by measuring a shift in space of each of the pair of xcoordinates thereof relative to an expected location of each xcoordinate, and identifying a twist deformation by determining whetherone or more twist amounts individually exceed a threshold.
 17. Thesystem of claim 10, wherein the extracting the geometric location dataincludes: identifying an x, y and z coordinate of a plurality ofvertical reference points along a hard face plane of each shroud inspace, and identifying an angular orientation of each hard face plane inspace; and wherein the inspecting includes: measuring a contact gapbetween hard face planes of each pair of adjacent blades in thethree-dimensional virtual rendering at each of the plurality of verticalreference points on each hard face plane, identifying a minimum contactgap amongst the contact gaps at each of the plurality of verticalreference points, and identifying a contact gap violation by determiningwhether the minimum contact gap exceeds a threshold.
 18. The system ofclaim 10, further comprising: based on the inspecting, changing acircumferential position of at least one blade within the blade stagewithin the three-dimensional virtual rendering of the shrouds of theblade stage; and ensuring a moment weight balancing of the blade stagedoes not exceed a threshold.
 19. A system for virtually inspecting ablade stage, the blade stage having known dimensions, the systemcomprising: a digitizing device for obtaining a three-dimensional modelof at least a shroud of each blade of the blade stage; a computer systemincluding at least one module configured to perform the followingprocesses: extracting a geometric location data of a plurality ofreference points of each shroud from a three-dimensional model of ashroud of each blade of the blade stage created by digitizing using adigitizing device; generating a three-dimensional virtual rendering ofthe shrouds of the blade stage based on the geometric location data andthe known dimensions of the blade stage, the three-dimensional virtualrendering including a rendering of the plurality of reference points ofeach shroud, wherein the generating includes: radially positioning eachshroud relative to a common axis based on a shroud radius of the bladestage, and circumferentially positioning each shroud about the commonaxis using a spacing depending on the number of blades in the bladestage, inspecting the blade stage using the three-dimensional virtualrendering by identifying at least one of an axial deformation, a radialdeformation, a twist deformation, and a contact gap violation; andmodifying at least one blade to at least reduce the at least one of theaxial deformation, the radial deformation, the twist deformation, andthe contact gap violation.
 20. The system of claim 19, wherein theextracting the geometric location data includes: identifying xcoordinates of a pair of corresponding axial reference points of thehard face planes for each pair of adjacent shrouds in space; and whereinthe inspecting includes: measuring an axial overlap between hard faceplanes of each pair of adjacent blades in the three-dimensional virtualrendering based on the x coordinates of the pair of corresponding axialreference points, and identifying the axial deformation by determiningwhether one or more axial overlaps individually exceed a threshold.